In-line Transport Logic Gate

This is similar to the proposal "Logic states on buildings and transports", but I would propose something that provides direct control over a transport lane:
A new part (1x1x1, size of the 'connector' parts) with one input and one output on opposite sides, so it could be placed in-line along a transport.
The dialog for the part would have a way to link it to a single storage (sort-of like the existing import/export interface?).
The dialog would also have threshold controls similar to the alert controls for a storage, as well as a toggle to indicate that the gate is either switched on or switched off when the threshold is met.
Multiple gates could be linked to the same storage, but they would be independently configured.
I've had a couple of use cases where something like this would have been helpful - such as producing ammonia from hydrogen if the sour water stripping is not producing enough ammonia, but not to use hydrogen if the ammonia storage is mostly full.

i just came to suggest this, i NEED this